1. Field of the Invention
The present invention relates to a rolling mill drive with gear-type joint spindles arranged between driveable rolls and the gear units of the driveable rolls and equipped with a device for circulatory or pressure lubrication of the gear units. Each articulated spindle has a grooved oil supply ring connectable to an oil supply, wherein oil can be supplied through a central duct of the spindle shaft to the gear-type joints, and with a stationary housing surrounding the spindle shaft at a distance and serving for the oil discharge, and with an oil delivery pump connectable on the pressure side to the oil supply rings and interacting with an oil cooler.
2. Description of the Related Art
When rolling, for example, comparatively thin and wide strips, it is necessary to displace the work rolls axially in the roll stand by a certain adjustment range for correcting any planarity errors of the rolled material and, if necessary, to adjust the width of the roll gap in accordance with different rolling schedules. For this purpose, an adjustment drive effects the axial displacement of the work rolls by exactly predetermined distances within the roll stand, while the rotary drive of the work rolls takes place in the known manner through gear-type joint spindles which are in connection with drive motors between the driveable work rolls and driving gear units. The gear-type joint spindles must be constructed in such a way that they compensate the axial and vertically adjustable displacements of the work rolls within the roll stand, on the one hand, and that they transmit the full drive power, for example, from pinions, to the work rolls. The interacting wobblers in the spline gearings are subjected to high frictional forces and develop heat as a result, and must be continuously supplied with lubricant for reducing the sliding friction and the temperature increase. For the purpose of a problem-free lubrication and cooling of the gear-type joints, the prior art provides for a circulatory oil lubrication which ensures a problem-free supply of all lubrication points of the gear-type joints with lubricant and, moreover, ensures the required discharge of the friction heat from the gear-type joints.
EP 0 324 168 B1 discloses a rolling mill drive with axially displaceable gear-type joint spindles arranged between drive shafts and driven rolls between drive necks of pinions and drive necks of the rolls. Arranged at each spindle head is a wobbler provided with a spiral toothing and a coupling sleeve provided with an internal toothing and surrounding the wobbler, wherein the coupling sleeve, in turn, is connected to a drive gear-type neck or to a roll neck. Provided for this drive arrangement is a circulatory oil lubrication in which an oil supply ring is arranged in a stationary oil housing, wherein the oil supply ring surrounds the spindle shaft and is provided on the side facing the spindle shaft with an internal annular groove which is in open connection with an oil duct leading to the spindle axis. This oil duct leads into a concentrically arranged central duct from which the gear-type joints are supplied in a suitable manner with lubrication oil. Oil reservoirs are provided on the spindle heads on both sides, wherein the oil reservoirs are each connected to an oil housing rotatably mounted on the coupling sleeve, wherein, for this purpose, the rotatable coupling sleeve is provided with a labyrinth-type seal whose other sealing elements are connected to the housing.
During a roll change, at least the spindle heads on the side of the roll stand have to be removed from the coupling sleeve on the side of the rolls; this requires a very labor-intensive assembly because of the oil housing with labyrinth-type seals located on this side. Moreover, an oil contamination is unavoidable during operation, wherein, for example, in the case of labyrinth-type seals, experience has shown that water/emulsion cooling liquid can penetrate into the oil reservoirs.
DE 1 902 894 discloses an gear-type joint spindle for rolling mill drives with a device for circulatory lubrication which includes a grooved ring for effecting the oil supply, wherein the grooved ring sealingly surrounds the spindle shaft and is mounted so as to be non-rotatable relative to the spindle shaft, and wherein oil can be supplied from the ring through ducts of the spindle shaft to the gear-type joints. The device further includes a non-rotatable housing for effecting the oil discharge, wherein the housing surrounds the spindle shaft at a distance. The device further includes an oil delivery pump which on an intake side is in connection with a cooling device, preferably with the intermediate arrangement of a cooling device, and is on the pressure side in connection with the grooved ring. The housing has in the area where the spindle shaft extends through the housing lamella walls which are engaged with play in a labyrinth-type manner by lamella rings provided on the spindle shaft.
This arrangement also requires a relatively complicated assembly when rolls are exchanged resulting in disadvantageously long idle times. On the other hand, in this arrangement, it is also not possible to exclude with absolute certainty a contamination of the circulating oil, which makes it necessary to exchange the oil after relatively short periods of operation, or the circulating oil must be purified in the known manner with the use of an oil centrifuge, which is also very expensive.
DE 37 06 577 C2 discloses a rolling mill drive with gear-type joint spindles and wobblers provided with spiral toothings mounted on the ends of the spindle shafts as well as connection sleeves provided with internal toothings engaging around the wobblers, wherein the connection sleeves are supported at both ends of the spindle shaft by means of support balls and pressure pistons; the drive further includes a circulatory oil lubrication. The central duct of this oil lubrication is equipped with bores and oil lines for lubricating all friction surfaces between the wobbler and the axially displaceable guide sleeve and the support balls which are displaceable against the pressure pistons and the spiral toothings which are displaceable against the internal toothings.
In this known rolling mill drive, the spindle heads are also located within the oil collection housings from where the oil return is pulled off and is returned by means of a pressure pump once again into the circulation.
This drive has in principle the same disadvantages as the rolling mill drives discussed above, i.e., a progressive contamination of the oil during the operation and difficult assembly conditions for the roll exchange in the area of the spindle heads on the side of the roll stand.